(fl) For the same angle of incidence 45°, the angle of refraction in two transparent media; I and II is 20° and 30° respectively. Out of I and II, which medium is optically denser and why?
(b) Light enters from air to diamond which has refractive index of 2.42. Calculate the speed of light in diamond, if speed of light in air is 3.00 x 108 m ${{s}^{-1}}$